The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Radial shaft seals are commonly provided for sealing between a housing and a rotary shaft passing through the housing. One problem with radial shaft seals is that shaft offset or other misalignment and/or dynamic run out conditions relative to the housing bore can cause the seal lip to be unable to follow and thus lift off the shaft, allowing fluid to escape and leak past the seal. Radial shaft seals often utilize a fluid being sealed (oil, water) to lubricate and cool the seal lips. However, during some periods of operation, such as the spin cycle of a washing machine, the fluid (water) may be missing from the seal environment and therefore, does not provide the lubricating or cooling function. Accordingly, the present disclosure provides a radial shaft seal capable of accommodating large amounts of shaft misalignment, radial offset and dynamic run out while also being pre-lubricated.
The radial shaft seal of the present disclosure provides an annular outer rigid insert adapted to reinforce an elastomeric rind portion surrounding and extending axially along the tubular portion of the outer rigid insert to effect a sealing press-fit into the interior of a housing bore. The elastomeric rind portion terminates and wraps inward around an inward radiating wall end portion of the outer rigid insert where the elastomer forms into a flex portion that extends axially, which is radially spaced from the tubular portion of the outer rigid insert. This flex portion terminates and is attached to an elastomeric bearing portion of the seal. The elastomer flows axially along and around the outside of an inner rigid insert where it joins with the elastomer of the reinforced bearing portion and forms a pair of flexible seal lips that hug and seal around the shaft, the sealing action of a first seal lip is intensified and assured by a garter spring mounted around the flexible seal lip while a second seal lip, along with the first seal lip, defines an enclosed lubrication chamber. The lubrication chamber contains lubrication for the seal lips and bearing portion.
The reinforced elastomeric bearing portion includes a plurality of raised ribs the innermost bearing surfaces of which lie tangentially to the shaft surface and which have either a flat or slightly convex shape but which includes rounded edges at the intersection of the sides of the raised ribs and the bearing surfaces. The bearing surfaces of the ribs form an acute angle with the surface of the shaft which facilitates the carrying of liquid fed from the grooves between the ribs and which forces the fluid into the acute angles thus wedging the fluid between the reinforced elastomeric bearing interior surfaces and the shaft exterior creating a full film elastohydrodynamic lubrication regime between the reinforced bearing interior and the shaft exterior. The reinforced bearing portion being attached to the adjacent flexible seal lips causes the bearing and seal lip portions to be held circular and concentric, and to track true to the shaft being sealed regardless of considerable shaft to bore misalignment, offset and dynamic run out, thus assuring excellent sealing efficiency.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.